HERKYNA (or Hercyna) was the NaiadNymph of the stream Herkyna near Lebadeia in Boiotia (central Greece). She was a childhood companion of Persephone, and a goddess of the chthonian shrine of Trophonios.

Her name probably means guard-dog, from eruô, to guard, and kyôn a dog, or alternatively, she-who-wards-off, erukô. The story given by Pausanias, however, has it derive from herkos, a bird-catching net or noose. Herkyna appears to be closely identified with the goddess Hekate. Both were childhood companions of the goddess Persephone; and chthonian (or underworld) goddesses associated with dogs.

PARENTS

Nowhere stated

ENCYCLOPEDIA

HERCYNA (Herkuna), a divinity of the lower world, respecting whom the following tradition is related. She was a daughter of Trophonius, and once while she was playing with Cora, the daughter of Demeter in the grove of Trophonius, near Lebadeia in Boeotia, she let a goose fly away, which she carried in her hand. The bird flew into a cave, and concealed itself under a block of stone. When Cora pulled the bird forth from its hiding place, a well gushed forth from under the stone, which was called Hercyna. On the bank of the rivulet a temple was afterwards erected, with the statue of a maiden carrying a goose in her hand; and in the cave there were two statues with staves surrounded by serpents, Trophonius and Hercyna, resembling the statues of Asclepius and Hygeia. (Paus. ix. 39. § 2.) Hercyna founded the worship of Demeter at Lebadeia, who hence received the surname of Hercyna. (Lycoph. 153, with the note of Tzetzes.) Hercyna was worshipped at Lebadeia in common with Zeus, and sacrifices were offered to both in common. (Liv. xlv. 27.)

Source: Dictionary of Greek and Roman Biography and Mythology.

Pausanias, Description of Greece 9. 39. 2 (trans. Jones) (Greek travelogue C2nd A.D.) :
"[The town of Lebadeia in Boiotia] is separated from the grove of [the chthonian oracular daimon] Trophonios by the river Herkyna. They say that here Herkyna, when playing with Kore [Persephone], the daughter of Demeter, held a goose (khên) which against her will she let loose. The bird flew into a hollow cave and hid under a stone; Kore entered and took the bird as it lay under the stone. The water flowed, they say, from the place where Kore took up the stone, and hence the river received the name Herkyna. On the bank of the river there is a temple of Herkyna, in which is a maiden holding a goose in her arms. In the cave are the sources of the river and images standing, and serpents are coiled around their sceptres. One might conjecture the images be of Asklepios and Hygeia, but they might be Trophonios and Herkyna, because they think that serpents are just as much sacred to Trophonios as Asklepios."

N.B. It appears that Pausanias has ommitted certain details of this story, which seems to be a local version of the tale of the abduction of Persephone. The goose appears to be the lure (rather than the usual narcissus flower), and the burried stream the entranceway to the upper world for the god Haides.